Rewritable optical discs have had a maximum storage capacity of approximately 650 MB, but this limit has been pushed to several gigabytes by the introduction of DVD-RAM discs, a phase-change type of storage medium. Used in conjunction with practical implementations of MPEG (particularly MPEG-2), a digital AV data encoding standard, DVD-RAM is not limited to computer applications and will soon find widespread use as a recording and playback medium in the audio-video (AV) and even home entertainment industries.
With the start of digital broadcasts in Japan it has become possible to multiplex and simultaneously transmit the video, audio, and data portions of plural programs to the MPEG transport stream (“MPEG_TS” below). Digital broadcast recorders using hard discs or DVD media to record these programs are also available.
These next-generation digital broadcast recorders typically record digital broadcasts in the original broadcast format without converting the MPEG_TS of the broadcast, and are expected to record AV data from an external line input using the MPEG_TS so that the recorder does not need to internally handle both the MPEG program stream (“MPEG_PS” below) and the MPEG_TS.
However, because the current DVD logic standards (including the DVD-Video standard, DVD-Audio standard, DVD Video Recording standard, and DVD Stream Recording standard) use the MPEG_PS for AV stream recording, MPEG_TS to MPEG_PS conversion (TS2PS conversion) is required in order to convert content recorded in the MPEG_TS format, such as by the above-noted digital broadcast recorder, to the DVD-Video format, for example.
Converting a stream multiplexed to the MPEG_TS to MPEG_PS, however, involves a complex recalculation for decoder buffer management, the TS2PS conversion is time-consuming, and often involves re-encoding the elementary stream, resulting in degraded image quality and sound quality.